Riot police in Iran have clashed with protesters in the capital over sharp falls in the currency, the rial.

Tear gas was used to disperse the demonstrators, some of whom were setting fire to tyres and rubbish bins. There were many arrests, reports say.

Eyewitnesses told the BBC that scores of people gathered outside the central bank, calling for the governor to stand down, chanting anti-government slogans.

The rial has plummeted to record lows against the US dollar in recent days.

Analysis

By Kasra NajiBBC Persian

It is not every day that you see anti-government protests in Iran, let alone by those who have, on the whole, done very well under President Ahmadinejad and the Islamic regime.

What has led them to frustration is the continuing free fall of the value of the Iranian rial - in recent days by 15% per day. This speed of devaluation has made it very difficult for them to buy and sell as prices change on hourly basis.

Worse still, they find President Ahmadinejad, who seems to have little idea about how to arrest the downward spiral of the currency, blaming them for the crisis.

It is clear that Mr Ahmadinejad's many enemies in various centres of power have begun a push to remove him before his term ends in June 2013. He may be the first big casualty of the sanctions against Iran. But Mr Ahmadinejad is a fighter and his removal may not be that easy.

Money dealers were joined by traders from the nearby central bazaar, reports say.

Amateur video footage posted online appeared to show hundreds of people marching towards Iran's central bank.

One eyewitness, who gave his name only as Omid, told the BBC that the Sabze Maydon area within the bazaar was closed down and some shop windows were smashed.

He said the government had closed the currency exchange shops, hoping to curtail the turmoil.

A senior Iranian police commander confirmed to Ilna that "a limited number of people protested in front of the bazaar," but he said the bazaar was not closed.

Hundreds of police are also reported to have rounded up and arrested illegal money changers in the capital.

Iranian media reaction

The conservative daily, Khorasan, asked: "Mr Ahmadinejad, are you the country's president?" It said the president had failed at a news conference on Tuesday to say "what 'programmes' and 'new plans' the government has to resolve the situation".

The reformist newspaper, Etemad, carried an editorial headlined "Why can't you?" saying that "once again Ahmadinejad took no responsibility for the chaotic situation".

The conservative news website, Baztab-e Emruz, pointed to the negative impact of the president's remarks on the decline in the rial's exchange rate. "An hour after Ahmadinejad's news conference... the rate of the dollar, which had reduced to 3,200 tomans [32,000 rials approx] in the afternoon, increased to 3,550 again," it said.

The moderate Mardom Salari noted the "contradictory views" of Majlis Speaker Ali Larijani on the instability of the exchange rate. On Tuesday Mr Larijani told the Fars news agency: "Eighty percent of our economic issues and problems are related to the system of management."

Source: BBC Monitoring

Tehran's bazaar is traditionally the biggest financial ally of the Iranian regime. The bazaar is said to have bankrolled the 1979 Islamic revolution.

The political core of the bazaar is the Islamic Allied Society or Motalefeh, a political group loyal to Iran's Supreme Leader Ayatollah Ali Khamenei.

One woman in the city of Malayer told the BBC that Iranians were "very angry with the regime".

"The situation is becoming worse and worse every day," she said.

"I work in the main hospital in the city and we are encountering some serious problems. We can't buy necessary medication because prices go up by 70% a day."

President Ahmadinejad has blamed Western sanctions for the fall in the rial, saying they amounted to an economic war.

However, many Iranians accuse him of financial mismanagement.

US officials say the slide reflects the success of US economic sanctions targeted at Iran's controversial nuclear programme.

Even so, US Secretary of State Hillary Clinton said the Iranian government should bear responsibility for what was happening inside Iran.

"They have made their own government decisions - having nothing to do with the sanctions - that have had an impact on the economic conditions inside of the country," she said.

"Of course the sanctions have had an impact as well, but those could be remedied in short order if the Iranian government were willing to work with the P5+1 and the rest of the international community in a sincere manner," she added, referring to a negotiating group including the five permanent members of the UN Security Council and Germany.

Meanwhile, Ayatollah Khamenei said in a speech that the Iranian people would never submit to pressure from abroad.

Iran would put this crisis behind it, he was quoted by Iranian news agencies as saying.